Which preposition to use with serener

than Occurrences 1%

Mrs. Cadurcis, who, indeed, was only a child of a larger growth, became scarcely less attached to the Herbert family than her son; she felt that her life, under their influence, was happier and serener than of yore; that there were less domestic broils than in old days; that her son was more dutiful; and, as she could not help suspecting, though she found it difficult to analyse the cause, herself more amiable.

Which preposition to use with  serener